The invention concerns a method for operating a vehicle having an automatic, continuously variable gear ratio transmission, in particular, a passenger automobile. More specifically, the invention concerns a method for operating a vehicle wherein the transmission gear ratio, and possibly the throttle valve angle, is controlled as a function of the depression of the accelerator pedal, and possibly also as a function of the engine speed.
In commonly known automatic, continuously variable gear ratio transmissions, a control unit, which could be formed by a cam plate, for example, is used for adjusting a correcting element, which determines the transmission gear ratio. The control unit is typically fixedly connected with an accelerator pedal, or a throttle valve in carburetor engines. Accordingly, each accelerator pedal or throttle valve position is associated with a defined engine speed and a defined transmission gear ratio. In other words, the vehicle is controlled as a function of the depression of the accelerator pedal.
In using such transmissions to obtain the most favorable possible fuel economy, the transmission gear ratio is rapidly increased to its maximum value as the vehicle accelerates, and thereafter maintained at this value, even at small accelerator pedal angles. Frequently, in a vehicle having a transmission controlled in this manner, the maximum traveling speed of the vehicle cannot be attained at the maximum transmission gear ratio, which corresponds to a speed-increasing or overdrive gear ratio. However, in order to solve this problem, there have been provided systems wherein the gear ratio becomes smaller as the accelerator pedal is depressed beyond a specified accelerator pedal position, or throttle valve angle, in the vicinity of the full acceleration position of the accelerator pedal. The full acceleration position of the accelerator pedal is the position in which the throttle valve is fully opened. These smaller gear ratios result in larger engine speeds. When the accelerator pedal is fully depressed, a transmission gear ratio is set so that the maximum engine speed, the maximum traveling speed of the vehicle, and maximum engine power are attained.
However, with a transmission controlled in this manner, at complete or nearly complete depression of the accelerator pedal from a travel condition at a low load, the maximum transmission gear ratio, which is the most favorable for fuel consumption, can never be set; rather, only a lower gear ratio, which corresponds to an accelerator pedal position associated with a greater vehicle traveling speed and a less favorable fuel consumption condition, is set.